How Clash said. You need to know what species they are and make sure that species is "polygynous" (allows multiple queens to peacefully live together). As for the rest it's totally the same as having a single queen.

If they aren't polygynous they are likely going to kill each other straight away.

There is an exception if they are pleometric though. Pleometrosis is a behaviour observed in different species of ants which involves multiple queens starting a colony together but when the first workers hatch ending up killing each other until the strongest queen survives.